1. Field of the Invention
This invention relates to electric arc welding apparatus and, more particularly, to a system in which a welding helmet automatically rotates down before an arc is struck.
2. Description of the Art
In the technology or electric arc welding, there are primarily three types of systems: (a) a consumable metal rod coated with a solid flux; (b) tungsten inert gas (TIG); and (C) consumable metal inert gas (MIG). As in all electric arc welding systems, the welder must, before any welding can be done, strike an arc so that the necessary heat is formed to meld the work metal and the welding rod. In order to provide an aesthetic, strong weld, the arc must be formed as close as possible to the area where the weld is needed; otherwise, the heat from the arc will meld and weaken the body of the work. As the welder cannot see the work whenever an ultraviolet face shield of the helmet covers his face, the welder must strike the arc as quickly as possible after covering his face to avoid inadvertently moving the welding rod.
If the welder strikes the arc before he covers himself, he can accurately position the arc, but this invites physical and eye damage. The preferred technique is to bring the tip of the welding rod as close to the work area as possible while the helmet is in its raised position and quickly let the helmet fall just before the arc is struck. This takes tremendous skill on the part of the welder because, if the helmet drops too fast, the welder's reflexes cause the tip of the welding rod to jump, and if the helmet is dropping too slowly, the welder's hand will have a strong tendency to wander.
U.S. Pat. No. 4,937,879 (to Hall et al) teaches one solution to this problem. This patent discloses a helmet face shield actuator cylinder attached to the face piece of the helmet, and the piston is attached to the stationary headband. Although this patent teaches automaticaly lowering the face piece and preventing the formation of the arc until after the face piece is in place, extra weight is added to the moving face piece, making the welder less than comfortable. In addition, different helmet designs require a specially designed actuating means, and Hall et al use a relatively complex circuit for controlling movement of the face piece and striking of the arc.